The event which is being billed needs to occur before January 1st. The funds however have until March to be used I believe. It basically allows the time for December bills to be processed if that makes sense.
This happened to me last year. It's the same reason you can't use 2016 FSA funds to pay for a bill that occurred on December 31, 2015 even when the bill shows up in January.
It's why the optometrists are so busy in December. Any leftover funds are for new sunglasses for the family.
Last edited by PikeAV8R; 12-27-2016 at 09:25 PM.
Reason: Addition